1. Field of the Invention:
This invention relates to an endoscope light source apparatus which can output a white color light and a field sequential light.
2. Related Art Statement:
Recently, there is extensively used an endoscope (called also a scope or fiber scope) whereby organs within a body cavity can be observed by inserting an elongate insertable part through the body cavity and, as required, various therapeutic treatments can be made by inserting treating instruments through a treating instrument channel.
Various electronic scopes using such solid state imaging device as a charge coupled device (CCD) are also suggested. Such electronic scope has advantages that the resolution is higher than in a fiber scope, it is easier to record and reproduce picture images and such picture image processing as the enlargement of picture images or the comparison of two picture images is easier.
Among systems of imaging color picture images of the above mentioned electronic scope, there are such field sequential type sequentially switching an illuminating light to R (red), G (green) and B (blue) as is shown, for example, in the publication of Japanese patent application Laid Open No. 82731/1986 and such simultaneous type wherein a filter array in which color filters respectively transmitting such color lights as of R, G and B are arranged in the form of a mosaic is provided on the front surface of a solid state imaging device as is shown, for example, in the publication of Japanese patent application Laid Open No. 76888/1985. The field sequential type has an advantage that the number of pixels can be made lower than in the simultaneous type. On the other hand, the simultaneous type has an advantage that no color smear will be produced.
The above mentioned electronic scope is made in many kinds by its using objects. For example, an insertable part of an outside diameter of about 10 mm. is used for an upper or lower digestive organ. On the other hand, for example, an insertable part of an outside diameter of about 5 mm. is usually required for a bronchus. It is physically and operatively unreasonable to use the same kind of imaging device and the same kind of imaging system for various electronic scopes of outside diameters of the insertable parts thus varying in a wide range. That is to say, for example, in order to realize an electronic scope for a bronchus (fine diameter), an imaging device of few pixels can not help being used.
Thus, in the case of few pixels, in order to prevent the reduction of the resolution, a field sequential type color imaging system whereby the object is illuminated in a field sequential system with lights of respective wavelengths of R, G and B and is imaged field-sequentially under the illumination and these images are combined and color-displayed is more advantageous than a simultaneous type imaging system using a color mosaic filter.
On the other hand, for the outside diameter of about 10 mm., it is advantageous in order to improve the picture quality to increase the number of pixels and to make the imaging system a simultaneous type.
Now, the above mentioned fiber scope or electronic scope is used generally as connected with a light source apparatus feeding an illuminating light adapted to each scope.
The illuminating method is different in the above mentioned fiber scope, field sequential type electronic scope and simultaneous type electronic scope. That is to say, a white color light required in the fiber scope and simultaneous type electronic scope and a light sequentially switched to R, G and B is required in the field sequential type electronic scope. However, the conventional light source apparatus can output an illuminating light corresponding to only one of the field sequential type electronic scope, simultaneous type electronic scope and fiber scope. Therefore, the user must prepare respectively different light source apparatus and make different operations depending on the kind of the scope and the economy and efficiency have been low.
By the way, the publication of Japanese patent application Laid Open No. 243625/1985 discloses a connecting system whereby a fiber scope provided with an image transmitting optical fiber bundle is connected to a control apparatus of an electronic scope provided with a field sequential type light source apparatus so that the image may be observed on such displaying picture surface as of a monitor television. However, with this system, a simultaneous type electronic scope can not be used and the image can not be observed with a naked eye by using a fiber scope.
Therefore, the present Applicant has suggested, for example, in the previously filed U.S. patent application Ser. Nos. 150,255 and 155,396 an endoscope light source apparatus which can output a white color light and field sequential light.
Now, a halogen lamp or xenon lamp is used for the illuminating means of such light source apparatus which can output a white color light and field sequential light. In such case, the emitted light of the lamp will be fed as a continuous light. However, in case a field sequential type electronic scope is used, the light emitted from the tip of this electronic scope will be intercepted during the CCD charge transferring period by the rotation of a color converting filter provided between the lamp within the light source apparatus and the light guide entrance end of the electronic scope and therefore approximately more than half the light will not be emitted. On the other hand, in case a fiber scope or a simultaneous type electronic scope is used, the above mentioned color converting filter will not be required. Therefore, the light emitted from the tip of the scope in this case will effectively use the light emitted from the lamp.
Thus, in case the fiber scope and simultaneous type electronic scope are used, the light amount of the light emitted from the tip of the scope will effectively use the emitted light of the lamp and therefore will be bright enough for the observation. On the other hand, in case the field sequential type electronic scope is used, during the CCD charge transferring period, the emitted light from the lamp will be intercepted by the light intercepting parts of the color converting filter, the light emitted from the lamp will not be effectively utilized and the total light amount emitted from the scope tip will greatly reduce. That is to say, there are disadvantages that, in case a field sequential type electronic scope is used, the light amount emitted from the scope tip will be less than in the case of a fiber scope or simultaneous type electronic scope, will be short and will not be enough to be fed to the observed object and the observing capacity will reduce.